If high efficiency is your preference then the Antec High Current Pro series is probably familiar to you. Legit Reviews just reviewed their most powerful model, providing up to 850W and sporting four 40A 12V rails to power the six PCIe power connectors. The fully modular design is great for keeping your case clean and the clear labellings on the PSU ensures you can properly balance the load between the 12V rails. It performed admirably but the retail price of ~$200 did disappoint Legit Reviews somewhat.

"Today we will be having a close look at the 850W version of the High Current Pro series, the HCP-850. The HCP-850 is a modular power supply with a very long list of features and a seven year long warranty. As all of the High Current Pro products, the HCP-850 also comes with an 80Plus Platinum certification, the highest currently available on a retail product..."